The present invention is directed to a wheelchair lift apparatus of the type appended to and supported by a vehicle. The invention enables a wheelchair bound passenger at ground level to enter and be supported by a platform which, upon actuation, lifts the wheelchair bound passenger into a vehicle opening in a safe and efficient manner. A unique configuration is provided for actuating a bridge plate/roll stop which acts to prevent the wheelchair from rolling from the platform during the lift operation and further acts as a bridge between the platform and the vehicle interior once it is safe for the passenger to exit the platform and enter the vehicle.
There has been a plethora of art dealing with the transport of wheelchair bound handicapped persons. Some of these devices are self supporting and can be rolled or otherwise pushed against a vehicle opening. Other such devices are appended to the bottom of a vehicle chassis while others are supported at or about the sidewall of the vehicle proximate the vehicle opening. All of these various configurations can benefit by the employment of the present invention. The invention, however, will be described by making reference to the latter embodiment for convenience.
Devices of this kind all must be provided with certain general design components dictated principally by the need to capture and lift the wheelchair bound passenger in a safe fashion as well as to enable the device to fold or somehow be made unobtrusive when not in use. Devices of this kind are generally shown in a series of patents assigned to Ricon Corp. typified by U.S. Pat. No. 5,605,431 issued on Feb. 25, 1997, the disclosure of which is incorporated by reference herein.
Specifically, wheelchair lift devices of the type disclosed in the ""431 patent include a mobile platform for receiving a wheelchair, a parallelogram mechanism for carrying the platform, a hydraulic system for actuating the platform through the parallelogram mechanism and a control unit to accomplish different motion patterns. The parallelogram structure enables the platform to proceed between ground level and a vehicle opening while maintaining a horizontal orientation for supporting the wheelchair bound passenger. This structure also provides for a storage orientation enabling the platform to swing in a ninety degree arc to assume a substantially vertical orientation once the passenger is on board to enable the vehicle to proceed in a normal fashion.
The parallelogram structure, in actuality, includes a pair of such structures, one being located on each side of the platform. Upon hydraulic actuation, these parallelogram structures can open or fold in order to carry out the motion patterns as noted above. There is also generally employed a second or lower parallelogram structure which is in sliding engagement with the upper parallelogram structure which facilitates stowage and other platform actuation orientations. Again, as noted, the details of these various structures are taught in a series of patents typified by U.S. Pat. No. 5,605,431. As such, no attempt will be made herein to discuss the details of these configurations.
In order to address certain safety concerns dictated not only by logic but also government mandate, it is necessary to provide roll stops on both the front and rear edges of the lift platform in order to prevent inadvertent egress from the platform during the lift operation. It is quite apparent from reviewing prior configurations of this kind that these roll stops must also be capable of rotating through an arc of travel to enable a wheelchair bound passenger to enter and exit the platform at appropriate locations. Specifically, the outer roll stop must rotate counterclockwise from a substantially vertical to substantially horizontal orientation acting as a ramp at ground level to enable a wheelchair bound passenger to be rolled on to the platform. At this instant, however, the inward roll stop must be at a substantially vertical orientation to prevent the wheelchair bound passenger from inadvertently traveling off of the platform and its inner edge.
As the hydraulics are actuated resulting in a lifting of the platform, both the outer and inner roll stops maintain a substantially vertical orientation thus capturing the wheelchair bound passenger on the platform. Once the platform reaches the vehicle entrance, the outer roll stop maintains its substantially vertical orientation but the inner roll stop must then travel in a clockwise arc to act as a bridge plate between the platform and the vehicle interior. This enables the wheelchair bound passenger to enter the vehicle for later transport.
The present invention has recognized a need to improve upon the way in which the inner roll stop is actuated to change its orientation as described. Specifically, devices of this kind have provided various cam and cable mechanisms to enable the inner roll stop to move from a blocking (vertical) orientation to a transporting (horizontal) orientation simultaneously as the wheelchair reaches the vehicle opening without human intervention. Likewise, as the wheelchair supporting platform is lowered from the vehicle opening towards ground level, this rather complex configuration of the prior art acts to simultaneously move the inner roll stop to a blocking orientation. This is an important feature for it does not require an operator to change the orientation of the roll stop for, to do so, may result in an inadvertent accident as the operator may on occasion forget to change the position of the inner roll stop due to mere human error or omission.
It is thus an object of the present invention to provide a mechanism for changing the orientation of an inner roll stop without the need for complex camming and cabling as is so often employed in the prior art. This and further objects of the present invention will be more readily apparent when considering the following disclosure and appended claims.
An advantage of the present invention involves an inner roll stop mechanism usable with a wheelchair lift having a platform movable between a raised position and a lowered position. The inner roll stop mechanism comprises a pivotal mechanism engaging said platform and a bridge plate for assuming a substantially horizontal orientation and a substantially vertical orientation as the platform proceeds between the raised position and the lowered position.